A conventional radar installation for small airborne platforms (e.g., light aircraft) uses a relatively small antenna, in comparison with ground based installations or large aircraft, having less gain. A magnetron is generally used with the small antenna because the magnetron is capable of generating a high power pulse in a small area, which allows the small antenna to have a greater range. The high power pulse is transmitted and a return signal is generated as a reflection of the high power pulse from an object, such as weather. The return signal is processed through a relatively narrow bandwidth to maximize a signal-to-noise ratio. For example, an Intermediate Frequency (IF) filtering bandwidth is matched in size to the information bandwidth of the transmitted pulse and is narrow relative to the intermediate frequency.
The magnetron may drift in frequency with a fluctuation of temperature and other factors, and the drift can be on an order of tens of megahertz for a low cost magnetron. This drift generally affects high-performance radar installations that have narrow bandwidth processing, and most magnetron radar installations include circuitry for tracking and compensating for magnetron drift.
One common practice is to use circuitry based on a tuned local oscillator, adjusted to track magnetron drift, that produces a fixed IF and that is followed by a fixed narrow bandwidth IF filter. One example is an analog Automatic Frequency Control (AFC) circuitry having a Voltage Controlled Oscillator (VCO). The VCO is typically constantly adjusted to center a mixed received signal (i.e., based on the return signal) at the fixed IF and within the IF filter bandwidth. The analog AFC circuitry, as well as the VCO, may experience performance variations, such may result from component variation, temperature, aging, and replacement of obsolete parts. These variations may limit the operational quality of the system, increase the size and complexity of the system, and/or require costly circuit components and custom factory alignment.
Additionally, the conventional magnetron radar installation typically has a single IF with a unique bandwidth, and an analog signal path is generally used for processing a single unique IF signal/bandwidth. To process multiple simultaneous and unique IF signals/bandwidths, a typical radar installation architecture uses multiple conventional receivers, each providing an analog signal path with each receiver generally subject to the aforementioned associated performance variations. The addition of receivers also increases an overall cost associated with the radar installation. Further, injection-locked magnetron based radar installations may be implemented with fewer performance variations, resulting from frequency drift, than the conventional magnetron radar installation but at significantly more expense and size than the conventional magnetron radar installation. Solid-state, non-magnetron based radar installations may also be implemented with fewer performance variations but tend to have inadequate power for the small antenna used in light aircraft installations.
Accordingly, it is desirable to provide a relatively cost-effective radar receiver without an analog AFC circuitry. In addition, it is desirable to provide a radar receiver having simultaneous processing of several IF signals of dynamically varying frequencies and bandwidths with a single analog signal path. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.